window.addEventListener('load',function(){
    let arrowl=this.document.querySelectorAll('.news-al');
    let arrowr=this.document.querySelectorAll('.news-ar');
    let divloop=this.document.querySelectorAll('.news-imgout');
    
    /* 鼠标经过时就显示左右箭头*/
    for(let n=0;n<divloop.length;n++){
    divloop[n].addEventListener('mouseenter',function(){
        arrowl[n].style.display='block';
        arrowr[n].style.display='block';
    })
    /* 鼠标离开 */
    divloop[n].addEventListener('mouseleave',function(){
        arrowl[n].style.display='none';
        arrowr[n].style.display='none';
    })
}
})